Thursday, February 27, 2014

The
convergent evolution of tail shapes in diving birds may be driven by
foraging style. Birds use their wings and specialized tail to maneuver
through the air while flying. It turns out that the purpose of a bird's
tail may have also aided in their diversification by allowing them to
use a greater variety of foraging strategies. To better understand the
relationship between bird tail shape and foraging strategy, researchers
examined the tail skeletal structure of over 50 species of waterbirds,
like storks, pelicans, and penguins, and shorebirds, like gulls and
puffins. They first categorized each species by foraging strategy, such
as aerial, terrestrial, and pursuit diving, and then compared the shape
and structure of different tails.

This
is a contrast of the typical elongate pygostyle of a diving bird (A),
the Adélie Penguin (Pygoscelis adeliae, specimen AMNH 623439) to the
typical short, dorsally deflected pygostyle of a non-diving bird (B),
the Northern Fulmar (Fulmarus glacialis, specimen AMNH 20697).

Credit: Ryan Felice; CC-BY

The convergent evolution of tail shapes in diving birds may be driven by foraging style, according to a paper published in PLOS ONE on February 26, 2014 by Ryan Felice and Patrick O'Connor from Ohio University.

Birds
use their wings and specialized tail to maneuver through the air while
flying. It turns out that the purpose of a bird's tail may have also
aided in their diversification by allowing them to use a greater variety
of foraging strategies. To better understand the relationship between
bird tail shape and foraging strategy, researchers examined the tail
skeletal structure of over 50 species of waterbirds, like storks,
pelicans, and penguins, and shorebirds, like gulls and puffins. They
first categorized each species by foraging strategy, such as aerial,
terrestrial, and pursuit diving, and then compared the shape and
structure of different tails.

Scientists found that foraging
style groups differed significantly in tail skeletal shape, and that
shape could accurately "predict" foraging style with only a small amount
of mismatch. In particular, underwater foraging birds, such as
cormorants, penguins, puffins, gannets, and tropicbirds, have separately
evolved a similarly specialized elongated tail structure, whereas
aerial and terrestrial birds have a short, dorsally deflected tail
structure. Moreover, each underwater foraging group, such as foot
propelled, wing propelled, or plunge diving, had a distinctive
tail-supporting vertebrae shape. According to the authors, the probable
separate evolution of the specialized tail in underwater-diving birds
may suggest that body structure adapted to the demand, or the need to
move the tail as a rudder during underwater foraging. In contrast, the
authors found no conclusive results when looking at the relationship
between tail shape and flight style.

Mr. Felice adds, "Previous
research has shown that diving birds evolve specializations in wing and
leg morphology to facilitate underwater locomotion. This study puts a
necessary focus on the tail, finding that this region of the body also
evolves in response to the demands of underwater movement."

Story Source:
The above story is based on materials provided by PLOS. Note: Materials may be edited for content and length.